Transnational criminal law (TCL) is at the forefront of contemporary legal scholarship, addressing the increasing complexity of crimes that transcend national borders, including organized crime, terrorism, human trafficking and corruption. This article critically examines the historical evolution and current challenges of TCL, with a focus on the interplay between international cooperation, national sovereignty and the harmonization of legal standards. Using the exile of Napoleon Bonaparte as a historical case study, the article traces the transformation of international criminal responsibility from the ad hoc political mechanisms of the nineteenth century to the codified procedures of the International Criminal Court and the Rome Statute and then to treaty-based global counteraction of crime. The analysis highlights persistent fragmentation in TCL, including inconsistencies in liability, corporate responsibility and sentencing, particularly in transitional and post-conflict societies. Special emphasis is placed on the necessity for legal harmonization, the protection of human rights and the development of effective enforcement mechanisms to address cross-border crime. The article employs comparative legal analysis, doctrinal research and policy evaluation to propose pathways for reform, including enhanced international cooperation, unified legal definitions and the integration of international human rights standards. The findings underscore the urgent need for a cohesive global framework to ensure justice, security and accountability in the face of evolving transnational threats.